The present invention relates to a system for providing information to mobile units like vehicles, and an information receiving apparatus.
In recent years, high-level road traffic systems called ITS (Intelligent Transport Systems) have been arranged. The high-level road traffic systems in this case refer to traffic systems that solve various problems attributable to traffic matters like traffic accidents, traffic jams, environmental pollution, etc., by driving techniques of information communication and electronic control.
As representative high-level road traffic systems, there are available a highway radio, a VICS (Vehicle Information and Communication System) called a road traffic information system, and an ETC (Electronic Toll Collection System) called an automatic toll collection system. However, in order to arrange these high-level road traffic systems, there has been a problem of high facility cost.
The highway radio and the VICS have conventionally been distributed as a part of the high-level road traffic systems for broadcasting road traffic information to mobile units like vehicles. The highway radio is for broadcasting road traffic information from a radio base station by utilizing a frequency of, for example, 1620 kHz.
The VICS is for broadcasting road traffic information from a radio base station such as a wave beacon, an optical beacon, an FM (Frequency Modulation) multiplex broadcasting station, etc. The highway radio and the VICS employ a micro cell structure having a plurality of micro cells arranged along a road, each micro cell having a radius of about a few km. Therefore, the highway radio and the VICS require a radio base station at each micro cell, and have a large number of radio base stations installed at every few kilometers.
Recently, in addition to the highway radio and the VICS, there has also been introduced an on-demand type information providing system in which a mobile unit transmits a request for information to an information center by radio, and the information center provides the requested information to the mobile unit. According to this on-demand type information providing system, a user who is on a mobile unit makes an access to the information center from a digital portable telephone, and gives a message to an operator about the information the user wants to receive. Then, this requested information is provided to the user through a car navigation system or the like.
As the conventional highway radio and VICS employ a micro cell structure as described above, it is necessary to install a large number of radio base stations at every few kilometers, which has had a problem of a very high installation cost.
Further, in the on-demand type information providing system, a user must make an access to the center each time the user wants to receive information. Therefore, this system has a problem in that it is not convenient to utilize this system, and that the quality of the information provision service is low.
It is an object of this invention to provide a system for providing information and an apparatus that receives the information in which it is possible to lower the cost and improve the quality of the information provision service.
The information providing system according to this invention comprises a transmitting station for transmitting multiplex information having a plurality of pieces of contents information to be provided to a mobile unit multiplexed, to a ground surface via a relay unit in the sky; and an information receiving apparatus that is mounted on the mobile unit, for receiving the multiplex information. Further, the information receiving apparatus comprises a receiving unit receiving the multiplex information; a self-position detecting unit detecting a self-position of the mobile unit; a memory unit storing a table that represents a relationship between extraction information that is used for extracting contents information from the multiplex information and position information relating to a position at which the mobile unit can exist; a retrieving unit retrieving the position information corresponding to the self-position from the table, and thereafter for retrieving the extraction information corresponding to the position information; and an extracting unit extracting the contents information from the multiplex information that has been received by the receiving unit, based on the extraction information retrieved from the retrieving unit.
The information receiving apparatus according to the present invention comprises a receiving unit mounted on a mobile unit, for receiving multiplex information that has been transmitted to a ground surface via a relay unit in the sky and that has a plurality of pieces of contents information multiplexed; a self-position detecting unit detecting a self-position of the mobile unit; a memory unit storing a table that shows a relationship between extraction information that is used for extracting contents information from the multiplex information and position information relating to a position at which the mobile unit can exist; a retrieving unit retrieving the position information corresponding to the self-position from the table, and thereafter for retrieving the extraction information corresponding to the position information; and an extracting unit extracting the contents information from the multiplex information that has been received by the receiving unit, based on the extraction information retrieved from the retrieving unit.
Multiplex information transmitted via the relay unit is received by the receiving unit that is mounted on the mobile unit. The self-position detecting unit in the information receiving apparatus detects the position of the mobile unit (hereafter, self-position). The retrieving unit retrieves the position information of the self-position from the contents of the table, and then retrieves the extraction information corresponding to the position information. Based on this, the extracting unit extracts contents information from the multiplex information that has been received by the receiving unit. The extracted contents information is the information corresponding to the position information relating to the self-position of the mobile unit. If the mobile unit moves, then the self-position detected by the self-position detecting unit and the position information and the extraction information retrieved by the retrieving unit change. Therefore, in this case, the contents information extracted by the extracting unit also changes. In other words, the extracted contents information automatically changes corresponding to the change in the self-position of the mobile unit.
Thus, based on the transmission of the multiplex information to the ground surface from the relay unit in the sky, it becomes possible to provide information over an extremely wider range than it has been able to provide by the conventional highway radio. In principle, the installation of a minimum one transmitting station is sufficient. Therefore, it becomes possible to lower the installation cost.
Further, the extraction information and the position information at which the mobile unit can exist are corresponded to each other in the table. At the same time, the self-position of the mobile unit and the contents information are corresponded to each other indirectly, and the extracted contents information is automatically changed along with the move of the mobile unit. Therefore, a user can handle the information providing system of this invention substantially better than the conventional on-demand type information providing system. As a result, it is possible to improve the quality of the information provision service.